71: EEPORT OF COMMISSIONER OF FISH AND FISHERIES. [72] \ 



The thermometer (Fig. 3) has already been described. 



The Magnaghi frame above described is a great improvement on the 

 wooden cases formerly furnished by the makers, but even this did not 

 prove entirely satisfactory in all respects, inasmuch as it could not be j, 

 secured to sounding wire, and could not, therefore, be used io series. 

 The fan failed to act occasionally, and the springs K and L were apt 

 to hold the case B in a vertical position by friction, thus i^reventiug [ 

 the turn- over at the proper time. 



Various devices have been used on the vessels of the commission for 

 capsizing the thermometer ; the Tanner case and the Bailie-Tanner case, 

 described in former reports, were, however, the most successful. They ! 

 were used with good results until the peculiar service of the Albatross :i 

 demonstrated the necessity for some arrangement by which the ther- 

 mometers could be used in series either on the souudiug wire or the ; 

 dredge, rope, which is frequently used as a temperature rope. It was >| 

 desirable also to reduce the weight and resistance as much as possible, i 

 We were troubled occasionally by the mercury shaking down from the i 

 catch reservoir into the tube, thus vitiating the reading. This was the j 

 result of jars of one kind or ant)ther. The speed of 600 to 800 feet per j 

 minute at which the sounding wire was hove in by steam was a fruitful 1 

 source of trouble, causing great vibration, which was complicated by ' 

 the jars incident to the rapid passing of centers by the single cylinder ., 

 reeling engine. These difficulties were subsequently overcome in the I 

 manner hereafter described. 



THE TANNER IMPROVED THERMOMETER CASE WITH THE SIGSBEE j 

 CLAMP, USED WITH THE NEGRETTI-ZAMBRA DEEP-SEA THERMOME- 

 TER (PLATE XXXIX). 



Fig. 1 shows the apparatus complete, and Fig. 2 a vertical sectiOnafl 

 elevation of the metal case containing the thermometer. 



NOMENCLATURE. 



a. Neck of the bulb. 

 h. Catch reservoir. 



c. Small receptacle. 



d. Partition confining mercury in shield surrounding bulb. 



e. Glass shield inclosing thermometer. 

 /. Thermometer case. 

 g. Thimble with rubber lining. 

 /(.. Spiral springs. 

 i. Cap. 

 /. Pivot. 



k. Slot for readiug scale. 

 I. Frame of cast brass. 



m. Guard. 



n. Propeller. 



0. Spindle. 



j>. Set screw. 



q. SJgsbeo clamp. 



fl 



